Identify and Treat Tomato Blight and Leaf Spot

Your tomato plants are susceptible and can die if you don’t know how to detect and react to blight and leaf spot infections.

Tomato blight and leaf spot are common problems that all tomato growers have been or will be faced with. Knowing how to treat these diseases will help you avoid losing your entire crop.

Tomato plant disease identification tips for blight and leaf spot gathered essential information on tomato plant leaf spot, early blight, late blight, and how to treat them.

Tomato Plant Leaf Spot – Signs and Treatment

Known as Septoria lycopersici, tomato leaf spot is a worldwide problem that affects tomato plants at any stage of development.

These are some of the primary symptoms and indications of tomato leaf spot:

• Lower (more mature) leaves show first signs of infection.
• Round, yellow spots develop on the underside of leaves.
• Spots quickly emerge on the tops of leaves turning black or brown with a black “dot” in the center.
• Heavily infected leaves turn yellow, then brown, eventually falling from the plant.
• Leaf spot symptoms will work their way up the plant, infecting stems as it progresses.

Tomato plant leaf spot disease septoria lycopersici

Fortunately, the fruit is rarely infected by this disease. However, the volume of the crop and vitality of the plant are adversely affected.

Treatment: Once a plant or crop is infected, all actions are to prevent the spread of leaf spot, as the disease cannot be eliminated without destroying infected plants.

• Carefully remove infected leaves and bury or burn them.
• Thin dense foliage to get more air and light to the remaining foliage.
• Stake the plants and ensure that they are spaced far enough apart to allow sufficient air and light penetration.
• Remove ground debris from around your tomato plants.
• Never compost infected plant matter.
• Use organic sulfur or copper-based fungicides (as directed) to prevent spores from germinating.
• Sanitize all gardening equipment with a 1:10 ratio of bleach and water after handling infected plant matter.
• Shoes, clothes, and gardening gloves are modes of spreading this type of fungi, and should be sanitized as well (washed in hot water and thoroughly dried on a ‘high heat’ setting).

Tomato Plant Early Blight – Signs and Treatment

Early blight is a form of tomato blight caused by the fungus Alternaria solani. Affected plants will underproduce, and because of leaf drop, the fruit is left vulnerable to sunscald.

Primary indications and symptoms of tomato plant early blight include:

• Lower leaves and stems develop dark (brown or black) circular spots.
• Early blight is highly recognizable by rings forming around the leaf spots.
• Unlike Septoria lycopersici, spots may appear on the fruit near the stem, eventually spreading over the fruit, causing it to rot on the vine.
• Lower leaves turn yellow and drop.

Tomato plant early blight disease identification and treatment

Since leaf spot and early blight infect tomato plants at the same time and under the same rainy or humid conditions, they are often confused with one another.

Treatment: The best treatment for early blight is prevention. Once plants are infected and the disease progresses, it becomes more resistant to fungicidal treatments.

The same treatment used for leaf spot (Septoria lycopersici) should be used for early blight (Alternaria solani).

The following measures will help prevent the spread of early blight:

• Purchase and plant disease-resistant species.
• Plant in raised beds to improve soil drainage and prevent the disease from spreading.
• Use watering methods which water the soil and not the plants. (splashing water provides an opportunity for this disease to spread quickly from plant to plant).
• Use black plastic or landscape fabric as land cover to provide a physical barrier between the fungus and the plant’s leaves.
• Remove all affected plants at the end of the season and destroy them.

Note: Early blight spores can survive for several years lying dormant in the soil. Use crop rotations to reduce the potential for infections.

Tomato Plant Late Blight – Signs and Treatment

Late blight is a form of tomato blight caused by the fungus Phytophthora infestans. Common throughout the United States, this disease occurs late in the growing season, often appearing only after blossom.

Primary indications and symptoms of tomato plant late blight include:

• Lower, older leaves are the first to show symptoms, manifesting as water-soaked grayish spots.
• Spots darken as the disease progresses and develop white fungal growth on leaf underside.
• The disease eventually infects the entire plant and its fruit.
• The most distinguishable trait of the disease is that plants are asymptomatic until late in the growing season, whereas other similar pathogens show symptoms much earlier in the season.

Tomato plant phytophthora late blight disease identification and treatment

Treatment: Measures for late blight treatment and prevention are identical to those of early blight.

If not controlled early on, this disease can easily spread throughout a field, causing total crop failure.

Now that you know how to deal with tomato blight, check out these Top 5 Tips To Help You Care For Your Tomato plants.

Tomato Plant Fungi

Don’t lose your tomato harvest to pathogens that can be controlled once you know what to look for.

In this article, you discovered essential information and treatment measures for tomato plant leaf spot, early blight, and late blight.

Your failure to act promptly when spot and blight symptoms appear can dramatically reduce the size of your crop, or annihilate it. By adhering to the measures outlined in this article, you will be more successful at salvaging your harvest and preventing the spread of these destructive pathogens.